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Commercial wood-burning stoves for large public saunas
31 kW of wood-fired output for rooms up to 1,270 cu ft. The Finnish commercial wood-burning standard for destination builds.
Pro 20 (WK200) and Pro 36 (WK360) are the commercial-scale wood-burning stoves Harvia builds for public saunas, resorts, and large communal installations. Pro 36 is the headline unit: 31 kW equivalent output, rooms up to 1,270 cubic feet, 132 lbs of stones stacked in three tiers, and a fire chamber that accepts firewood up to 15.3 inches long. These heaters end up in Nordic bathhouses, ski-town communal saunas, and destination wellness properties. The minimum ceiling spec is 81 inches — scaled for commercial rooms, not residential.
Fuel
Wood-burning
Output (Pro 36)
~31 kW equivalent
Room size
494 – 1,270 cu ft
Stone capacity
~132 lbs
Firewood length
Up to 15.3" (390 mm)
Min ceiling
81" (2,060 mm)
| Model | Power | Room size | Stones | Voltage | Notes |
|---|---|---|---|---|---|
| Pro 20 (WK200) | ~20 kW equivalent | 283 – 700 cu ft | ~88 lbs | — | — |
| Pro 36 (WK360) | ~31 kW equivalent | 494 – 1,270 cu ft | ~132 lbs | — | — |
From earnings calls, investor presentations, annual reports, and the Harvia product catalog.
“Muurame factory, the world's largest heater and sauna component factory: over 150,000 heaters per year.”
“In 2023, manufacturing [of wood-burning heaters] was almost fully moved to Muurame.”
Field knowledge from specialty dealers, commercial installers, and long-term Harvia operators. Stuff that isn't on the spec sheet.
Pro 36's 81-inch ceiling requirement comes from flue clearance and radiant heat distribution. In rooms with 78-inch ceilings you get hot spots at head height and insufficient steam at bench height. Spec Pro 20 (or Legend 240SL) instead if the ceiling can't clear 81 inches.
Both compete in the 700-1,200 cu ft range. Pro 36 has the larger fire chamber — fast heat-up, shorter recovery between sessions — but smaller stone capacity (132 lbs vs 450 lbs). Legend 240SL has the external wood-feed door that commercial operators prefer for safety. If the operator wants fast room turnaround, Pro 36 wins. If the operator values safety and consistent steam recovery across a long service day, Legend 240SL.
At 31 kW output, flue gas temperatures run 600-800°F during active burning. Single-wall pipe is not rated for that. Every commercial Pro 36 install requires full insulated Class A from heater collar to termination above the roof. Budget $2,500-$4,500 for the chimney package alone. Single-wall pipe on this output is code violation and fire hazard.
Pro 36 stones in commercial rooms running 12+ hours a day need full reload at 18-24 months. Elements below stone are fine — the reason is thermal cycling breaks the stones themselves. Budget the reload into operations schedule or the room loses steam output gradually without the operator noticing.
Commercial and destination wood-fired saunas, ski-town communal bathhouses, Nordic-inspired resort installs, large private cabin builds where the operator wants the Finnish commercial experience. Rooms 500+ cu ft with 81+ inch ceilings.
Warranty
2 years
Made in
Muurame, Finland
Launched
Long-running Pro series; current Pro 36 (WK360) is the current generation
Last Harvia mention
February 12, 2026
Q4 2025 earnings call + press release — Muurame capacity, US distribution expansion
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Earnings, investor calendar, stock chart, acquisitions timeline, and the rest of the Harvia product catalog live on our main hub.
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Product data sourced from Harvia Plc investor materials, earnings call transcripts, harvia.com, and harviagroup.com. Quotes attributed to specific sources. Insider notes reflect field knowledge from specialty dealers and commercial installers. SaunaNews is independent and not affiliated with Harvia Plc.